Our invention relates to femoral hip prosthesis and in particular to a spacer which can be placed under a collar on a femoral hip prosthesis to compensate for inadequate bone mass, particularly in revision surgeries.
Various types of femoral hip prosthesis are known and are used for surgical reconstruction of the femur. In general, these prostheses comprise a ball-shaped head mounted at an anatomical angle on a shank. The shank can be thrust into the medullar canal of a femur to mount the prosthesis on a resected surface of the femur. Many of these prostheses have collars near their proximal end which rest upon the resected surface. Both permanently attached, or integral, collars and replaceable collars are known.
In some cases, however, a patient's femur may have insufficient bone mass near the proximal end of the femur to support the collar or, during the revision surgery when a second operation is necessary, additional bone may be removed. To restore the prosthesis to an anatomically correct position, the prosthesis would protrude further out of the remaining femur, leaving a gap between the collar and the resected surface of the femur.